Troubleshooting guide

Additional BGP Configuration

<value> Specifies a privately defined community for routes serviced by this route map. This is a

numeric value that can be an integer from 1 to 4294967295 or string in the form aa:nn, where aa is the

AS number and nn is the community number. Multiple community number parameters can be present

in the command.

add Appends the listed community number to the end of the community attribute for routes serviced

by this route map.

internet Sets the community attribute to the reserved INTERNET community number for routes

serviced by this route map.

local-as Sets the community attribute to the reserved NO_EXPORT_SUBCONFED community

number for routes serviced by this route map. Routes containing this attribute should not be advertised

to eBGP peers.

no-advertise Sets the community attribute to the reserved NO_ADVERTISE community number for

routes serviced by this route map. Routes containing this attribute should not be advertised to any BGP

peer.

no-export Sets the community attribute to the reserved NO_EXPORT community number for routes

serviced by this route map. Routes containing this attribute should not be advertised to BGP peers

outside a confederation boundary.

none Removes all communities from BGP routes serviced by this route map.

Attributes, such as local preference and metric, can also be defined for the community string. A

discussion of the set commands used to define these community attributes begin with

Prepending

Private AS Numbers for Load Balancing on page 28.

Enabling an AOS Device to Send or Receive BGP Communities

A BGP neighbor must be configured for BGP communities before it is able to send or receive a

community attribute. Use the send-community standard command to enable this peer to accept a

community attribute and add the community attribute to any advertisement sent by this peer. This

command is issued from the BGP Neighbor Configuration mode:

(config-bgp-neighbor)#send-community standard

Deleting Communities from a Route

BGP communities are not completely standardized. External neighbors can place routes in a

community for which the local network does not define a policy or for which it defines a substantially

different policy. A network administrator might not want to apply the policies that the external

neighbor is requesting with the community attribute. As a result, the administrator might need to

remove certain communities from inbound routes in order to enforce the organization’s policies.

See Table 1 on page 14 for a summary of the well-known communities (for example,

INTERNET, NO_EXPORT_SUBCONFED, etc.) and the policy expected for these

communities.